K3合金复合涂层高温防护性能研究

采用电弧离子镀技术在K3镍基高温合金基材上分别沉积NiCrAlYSi涂层和NiCrAlYSi AlYSi沉积-扩散型复合涂层,研究两种涂层在1100℃下的高温氧化行为和900℃下的燃气热腐蚀行为.结果表明,NiCrAlYSi AlYSi复合涂层具有比单一的NiCrAlYSi涂层更加优良的抗高温氧化性能,而NiCrAlYSi涂层的抗燃气热腐蚀性能则优于NiCrAlYSi AlYSi复合涂层.     

AlYSi涂层组织结构及抗燃气热腐蚀性能

采用真空电弧离子镀技术在K465镍基高温合金基材上制备了AlYSi沉积-扩散型涂层。研究了真空退火处理前后涂层的组织结构,以及涂层在900℃下的燃气热腐蚀行为。结果表明,经真空退火处理后的AlYSi涂层主要由β-NiAl相组成,与基体结合良好;K465合金在热腐蚀过程中表面产生了大量的腐蚀剥落;AlYSi涂层在热腐蚀过程中表面形成了Al2O3保护膜,显著提高了合金的抗燃气热腐蚀性能。     

单晶高温合金铂改性铝化物涂层的高温防护性能研究

采用化学气相沉积(CVD)方法在单晶高温合金基体上制备了单一铝化物和铂改性铝化物涂层,研究了两种涂层的高温氧化性能和抗燃气热腐蚀性能。采用X射线衍射(XRD)、扫描电子显微镜(SEM)等方法分析了两种铝化物涂层的相成分和显微组织,结果表明:经1000℃氧化250h后,两种涂层的氧化动力学曲线均符合抛物线演变规律,Pt-Al涂层的抗氧化性能相对于单一Al涂层提高了55.5%,Pt元素的加入减缓β→γ′的相变速率,保证了高质量α-Al2O3保护膜的生成;经900℃燃气热腐蚀100h后,两种涂层的腐蚀动力学曲线均符合抛物线演变规律,Pt-Al涂层的抗燃气腐蚀性能相对于单一Al涂层提高了57.9%,Pt元素阻碍了内硫化的快速发生,保证Al2O3膜的完整性。     

AlSiY扩散涂层的高温氧化及热腐蚀行为

采用电弧离子镀技术和后续扩散处理,制备了AlSiY扩散涂层。同时研究了AlSiY扩散涂层在1000℃下的高温氧化行为和900℃下Na2SO4+NaCl混合盐中的热腐蚀行为。实验结果表明:AlSiY扩散涂层主要由β-NiAl相以及一些弥散分布的α-W、CoWSi相组成。氧化和腐蚀过程中涂层中β-NiAl相提供Al源在表面形成了连续致密的Al2O3膜,使涂层具有很好的抗高温氧化和抗热腐蚀能力。     

DZ40M合金表面纳米和垂直裂纹结构热障涂层的抗燃气热腐蚀性能

采用超音速火焰喷涂技术在定向凝固DZ40M钴基高温合金表面喷涂NiCrAlY金属粘接层,以纳米7YSZ团聚粉末为原料,分别利用大气等离子喷涂技术在粘接层表面制备了纳米结构和垂直裂纹结构7YSZ涂层,研究了高温合金基体和带涂层的基体在900℃下的燃气热腐蚀性能,分析了合金和涂层的燃气热腐蚀产物和过程。结果表明:两种结构热障涂层均大幅度提高了DZ40M合金的抗燃气热腐蚀性能,可避免基体在高温燃气热腐蚀中产生大量易剥离的腐蚀产物和氧化腐蚀孔洞;两种结构涂层在燃气热腐蚀后仍然保持完整并具有相近的燃气热腐蚀速率,垂直裂纹结构涂层中垂直于基体的贯穿裂纹在提高涂层应变容限的同时,并不会成为腐蚀介质快速渗入的通道。     

冷喷涂制备TiAl_3-Al复合层及其抗高温氧化性能

为了提高γ-TiAl合金的抗高温氧化性能,采用冷喷涂技术在γ-TiAl合金基体上喷涂纯Al层后进行热扩散处理,制备了厚约250μm的TiAl3-Al复合涂层,研究了该涂层在950℃下的长时间高温氧化行为,用X射线衍射仪(XRD)分析了复合涂层的相组成,用场发射电子显微镜研究了其形貌,用电子探针分析了其成分。结果表明:冷喷涂纯Al层致密,存在少量微裂纹和微气孔;TiAl3-Al复合涂层和基体之间生成了TiAl3相,TiAl3与Al的界面有空洞;γ-TiAl合金高温氧化70 h即失重,氧化产物为TiO2和Al2O3的混合物;TiAl3-Al复合涂层进入稳态氧化阶段后,增重缓慢,遵循近抛物线规律,高温氧化1 000 h后涂层仍完好,氧化产物主要为Al2O3相,还有微量的TiO2及钛氮化合物;TiAl3-Al复合涂层提高了γ-TiAl合金的抗高温氧化性能。     

电弧离子镀AlYSi涂层抗高温氧化性能研究

采用电弧离子镀技术在K465镍基高温合金基材上制备了AlYSi沉积-扩散型涂层,研究了K465合金和AlYSi涂层在1100℃下的高温氧化行为.利用SEM,EDX,XRD对氧化后的涂层表面和截面进行分析,结果表明:AlYSi涂层主要由β-NiAl相组成,氧化过程中涂层表面形成了Al2O3保护膜,显著提高了合金的抗高温氧...     

一种新型的抗高温腐蚀纳米复合膜的制备和性能

高温防护涂层往往通过显著提高Cr或Al的含量来达到防护的目的.20世纪80年代末研究者发现Co-Cr-Al合金微晶化可促进Al的选择性氧化,并对晶粒度影响合金氧化行为的研究深入到纳米尺度.基于对合金选择性氧化的理解,提出了一种从纳米尺度设计抗高温腐蚀性涂层的新思路,并用共电沉积技术在纳米尺度组装了能快速热生长Cr2O3或Al2O3型的纳米晶金属基/纳米Cr或(和)Al复合膜.通过与普通粗晶合金作对比,评述了这种新型纳米复合膜在高温腐蚀环境下具有优异性能的相关因素.最后展望了新型抗高温腐蚀纳米复合膜的潜在应用前景.     

高温镍基单晶合金NiCoCrAlYTa涂层的抗热腐蚀性能

以往,对高温镍基单晶合金上采用低压等离子喷涂制备的NiCoCrAlYTa涂层的热腐蚀性能研究较少.为此,采用低压等离子方法在镍基高温单晶合金上制备了NiCoCrAlYTa涂层,采用涂盐法研究了Na2SO4对试样在1 123 K空气中热腐蚀的影响,同时分析了NiCoCrAlYTa涂层的形貌及结构.结果表明:高温镍基单晶合金遭受了严重的热腐蚀,出现了内硫化和内氧化;NiCoCrAlYTa涂层由于表面生成了致密、保护性的Al2O3膜,以及涂层中Cr和Ta元素的作用而表现出优异的抗热腐蚀性能.结果证实,NiCoCrAlYTa涂层可以很好地提高单晶合金的抗热腐蚀性能.     

316L不锈钢表面耐高温氧化涂层的制备与性能

采用溶胶-凝胶法,以异丙醇铝为前驱体制备Al2O3溶胶,浸渍提拉后800℃下真空烧结,在316L奥氏体不锈钢表面制备出无裂纹的Al2O3涂层,研究涂层层数对316L奥氏体不锈钢高温抗氧化性能的影响.通过XRD和DSC对干凝胶粉末进行分析,并使用SEM研究Al2O3涂层表面形貌特征.涂层的高温抗氧化性能则使用氧化称重法来表征,对比有涂层试样和空白试样在高温氧化环境中的增重比.结果表明:制备出的涂层Al2O3颗粒均匀细小,有效阻止了氧化的进程,提拉3次制备的涂层的抗高温氧化效果最佳,在800℃使用的情况下至少延缓氧化时间165 h.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.